富硒饲料对仿刺参成参的饲喂效果研究

选用养殖规格仿刺参Apostichopus japonicus成参72头(40.31±1.27g),分别按蛋氨酸硒添加量0、0.2、0.4、0.6、0.8、1.0 mg/kg进行分组强化饲喂。试验进行28天,平均水温13℃,盐度27‰,p H 8.1,试验结束时分别测定各组成参的特定生长率(SGR)、摄食率(IR)、排粪率(FPR)、饲料转化率(FCR)和表观消化率(AD)。结果表明:特定生长率、摄食率和排粪率在硒添加量为0.6 mg/kg时分别达到最大值0.22%/d、0.0121 g/g·d、0.006 4 g/g·d,与对照组差异显著(P0.05);饲料转化率在硒添加量为0.4 mg/kg时达到最大值为18.37%,与对照组差异不显著(P0.05);成参对饲料中干物质、粗蛋白的表观消化率在硒添加量为0.6 mg/kg时达到最大值42.25%,79.61%,与对照组差异显著(P0.05),饲料粗脂肪的表观消化率在硒添加量为0.8 mg/kg时达到最大值95.52%,与对照组差异显著(P0.05)。综合生长性能和饲料利用情况,饲料中添加0.6~0.8 mg/kg的硒较为适宜。     

Selectivity of particle size by the shrimp Litopenaeus vannamei (Boone, 1931) larvae

Because of the filter‐feeding behavior of shrimp larvae, it is important to define precisely the size of the particle ingested in the different stages until postlarval stage where raptorial habits are more evident than the filter‐feeding lifestyle. Selectivity assays were conducted by using Polystyrene DVB particles with diameter between 1 and 50 μm as food. A group of organisms from each stage were put into the particle suspension for 15 min to let the polystyrene particles be ingested. The particle distribution in the media and the content of the gut of the larvae were characterized with digital image processing analysis. The results were compared using Ivlev selectivity formula, which compares the frequency distribution of each size of the particle in the media and in the gut of larvae. The results of selectivity were adjusted with a third‐order polynomial regression to determine the optimum and preferred size of the food particles for each larval stage between Zoea I and Postlarva I. It is concluded that the different larval stages of Litopenaeus vannamei may be considered as a single group of larvae who ingest foods with size between 5.71 and 20.33 μm. The optimal size of the food ingested was 14.42 μm wide.     

南方紫海胆摄食习性的初步研究

采用实验生态学的方法研究了成体南方紫海胆(Anthocidaris crassispina)的摄食和活力情况。结果表明,紫海胆在5种海藻共存的情况下,对不同海藻类具有不同选择性,日摄食率有显著性差异,对琼枝麒麟菜(Betaphycus gelatinum)的嗜食性最高,其次为半叶马尾藻(Sargassum hemiphyllum)、石花菜(Gelidium amansii)、石莼(Ulva lactuca),对刺松藻(Codium fragile)的喜好性较差。紫海胆的摄食受水温、海藻种类和自身体质量的影响,在23~27℃时活力和摄食状态最佳,水温升高和降低均会显著抑制其摄食;成体紫海胆对石莼、半叶马尾藻和琼枝麒麟菜的日摄食率有显著差异;在最适摄食水温下,紫海胆日摄食率随体质量增加呈显著的指数下降趋势。     

不同投饵率对花鳗鲡黑仔苗生长的影响

实验设置1.0%,1.5%,2.0%,2.5%,3.0%五个不同投饵率水平,在水温30℃的条件下,选取同一种饲料,对规格为3.67±0.30g的花鳗鲡黑仔苗进行40d的生长实验。结果表明,投饵率对花鳗鲡黑仔苗的相对增重率、特定生长率、饲料转化率均有显著性影响（p〈0.05）,花鳗鲡黑仔苗生长的适宜投饵率是2.0%;在此投饵率下,花鳗鲡黑仔苗的饲料转化率为（47.39±1.17）%,特定生长速率为（1.08±0.03）%/d,相对增重率为（52.49±1.04）%,存活率为100%。     

Effect of dietary Clostridium butyricum and different feeding patterns on growth performance,antioxidant and immune capacity in freshwater prawn (Macrobrachium rosenbergii)

An 8‐week study was conducted to evaluate the effects of different feeding patterns with dietary Clostridium butyricum supplementation on growth performance, antioxidant and non‐specific immune responses in freshwater prawn, Macrobrachium rosenbergii (0.39 ± 0.001 g). There were four feeding methodologies: feeding basal diet continuously (P1); feeding diet with 500 mg/kg C. butyricum continuously (P2); feeding diet with 500 mg/kg C. butyricum 5 days after 2 days of basal diet (P3) and feeding diet with 500 mg/kg C. butyricum 2 days after 5 days of basal diet (P4). The results revealed that prawns in P3 had the highest weight gain rate (WGR) and lowest feed conversion ratio (FCR) than the other groups. Haemolymph total protein levels and superoxide dismutase activity increased significantly in P2, P3 and P4 groups, while malondialdehyde content and anti‐superoxide anion levels decreased significantly compared to control. The mRNA expression of intestinal dorsal and Toll in P2 and P3 groups decreased significantly compared to control. Prawns in P3 exhibited improved growth performance, increased antioxidant capacity and enhanced immune function. We concluded that feeding diet with 500 mg/kg C. butyricum for 5 days after 2 days of basal diet was recommended for M. rosenbergii.     

Variations in larval walleye pollock feeding and condition: a synthesis

There was a strong association among concentrations of microzooplankton prey sampled from the walleye pollock, Theragra chalcogramma , larval habitat, gut contents of larvae, and their nutritional condition. Subsequently, hypothesized survival potentials linked to food availability were validated by independently determined mortality rates. We present evidence that a significant number of walleye pollock larvae were starving in 1991 but that fewer were starving in 1992. At some stations where prey levels were anomalously low in 1991, up to 40% of the larvae were in poor condition. There appears to be a 2-week period after first feeding when walleye pollock are vulnerable to starvation.     

Dietary protein/carbohydrate ratio in low‐lipid diets for Senegalese sole (Solea senegalensis,Kaup 1858) juveniles. Influence on growth performance,nutrient utilization and flesh quality

Four isoenergetic (21 kJ/g dry matter, DM) and isolipidic (65 g/kg DM) diets containing different crude protein/total carbohydrate (CHO) ratios: 60/26, 56/30, 52/34 and 48/38, were tested in 22 g Senegalese sole for 104 days. Apparent digestibility coefficients (ADC) were not affected by the treatments, and all groups presented extremely low starch ADC values (22.8%–36.5%). Replacement of dietary protein by CHO did not affect daily growth index (0.9–1.0), but significantly increased voluntary feed intake of fish. Regression analyses demonstrated that digestible protein content, rather than digestible energy, was the main dietary factor influencing such feeding activity (R² = .952). A significantly increased feed conversion ratio was observed in sole fed increasing CHO contents. The dietary protein/CHO ratio did not influence whole‐body composition. Sole fed the 48/38 diet showed the lowest efficiency in terms of N and energy utilization. PUFA were the most represented fatty acid fraction in fillet, regardless of the dietary protein/CHO ratio, mainly due to the high content of DHA. Senegalese sole increase feed intake under low dietary protein/CHO ratios to ensure an adequate N intake. Such compensatory mechanism seems to be triggered to satisfy a specific protein metabolic requirement for energy purposes as tissue accretion remained unchanged.     

不同投喂率和投喂频率对大杂交鲟幼鱼生长、体成分和生化指标的影响

为探讨大杂交鲟(Huso dauricus♀×Acipenser schrenckii♂)适宜投喂率和投喂频率,本实验分别设计了5个投喂率(0.4%、0.8%、1.2%、1.6%和2.0%)和5个投喂频率(1次/d、2次/d、3次/d、4次/d和5次/d),研究不同投喂率和投喂频率对大杂交鲟生长、体成分和生化指标的影响。投喂率实验中鱼初重(335.87±0.82)g,投喂频率实验中鱼初重(334.77±1.06)g,养殖周期为10周。结果表明,随着投喂率升高,实验鱼增重率、特定生长率、肝体比、脏体比、肥满度,肌肉粗蛋白、粗脂肪和肝粗脂肪含量显著升高(P0.05),血清谷丙转氨酶、谷草转氨酶和胃蛋白酶活性均显著升高(P0.05);饲料效率、全鱼和肌肉水分含量均显著降低(P0.05);全鱼粗脂肪含量,血清总蛋白、白蛋白和高密度脂蛋白胆固醇含量,肠脂肪酶活性呈先升高后降低趋势(P0.05)。随着投喂频率增加,实验鱼增重率、特定生长率和饲料效率无显著差异(P0.05);1次/d投喂频率组脏体比、肥满度和全鱼粗脂肪含量显著低于其他各组(P0.05),2次/d投喂频率组全鱼粗蛋白含量显著高于其他各组(P0.05)。不同投喂频率对实验鱼除血清葡萄糖含量以外的其他血清生化指标和胃肠消化酶活性或含量均无显著影响(P0.05)。综合以上结果认为,在300～600g大杂交鲟的养殖过程中日投喂率在1.2%～1.6%,投喂频率为2次/d比较适宜。     

Effects of feeding rate and frequency on growth performance,digestion and nutrients balances of Atlantic salmon (Salmo salar) in recirculating aquaculture systems (RAS)

A 10‐week study was conducted to investigate the effects of feeding rate and frequency on growth performance, digestion and nutrients balances of Atlantic salmon (Salmo salar) in replicated recirculating aquaculture systems (RAS). Replicated groups of juvenile salmon weighing 90 ± 2.5 g (mean ± SD) were fed a commercial feed (21.63 MJ kg^?1 gross energy) to designed feeding rate (1.4%, 1.6% and 1.8% body weight day^?1, BW day^?1) and feeding frequency (2 and 4 meals day^?1) combinations. Specific growth ratio varied between 1.15 ± 0.02 and 1.37 ± 0.16% day^?1, and feed conversion ratio ranged from 0.96 ± 0.03 to 1.16 ± 0.02. The nitrogen and phosphorus retention rates were from 36.50 ± 1.94 to 47.08 ± 5.23% and from 20.42 ± 1.05 to 38.59 ± 2.80%. Apparent digestibility coefficients (ADC) in dry matter, protein, lipid and energy showed no significant differences for all groups. However, fish fed at 1.6% BW day^?1 and 4 meal day^?1 groups had relatively better growth and nutrient retention efficiency compared to other groups. In addition, concentrations of nitrogenous and phosphorous compounds were also detected in this study. These results suggested that salmon of 100–200 g in RAS could in practice be fed at 1.6% BW day^?1 and 4 meals day^?1, taking environmental impacts into account.     

Effect of feeding time on dietary protein utilization and growth of juvenile Senegalese sole (Solea senegalensis)

The present study aimed to determine the effect of feeding time on growth and nitrogen excretion in juvenile sole. An 84‐day growth trial was conducted, in which food was supplied to three triplicate groups of juvenile Senegalese sole (3 g wet weight) at different schedules – diurnal, nocturnal and mixed. At the end of the growth trial, ammonia and urea excretion was assessed during a 24 h cycle. Improved growth (1.3% vs. 0.9% day^?1, specific growth rate), higher nitrogen retention (0.35 vs. 0.27 g N kg^?1 day^?1), lower ammonia excretion (209 vs. 272 mg N‐NH₄ kg^?1 day^?1) and lower total nitrogen excretion (278 vs. 352 mg N kg^?1 day^?1) were found in daytime‐fed fish compared with night‐fed fish. Fish in the mixed feeding regime showed intermediate values of ammonia and total nitrogen excretion, but did not differ from day‐fed fish regarding the other parameters. Results indicate that juvenile sole at a period of their life cycle appear to use more efficiently dietary protein for somatic growth under a diurnal than under a nocturnal feeding regime. This suggest that at least during a time‐window in the juvenile rearing a diurnal feeding regime might be more effective in the production of this species.